CLANG(1)			     Clang			      CLANG(1)



NAME
       clang - the Clang C, C++, and Objective-C compiler

SYNOPSIS
       clang [options] filename ...

DESCRIPTION
       clang  is  a C, C++, and Objective-C compiler which encompasses prepro-
       cessing, parsing, optimization, code generation, assembly, and linking.
       Depending  on  which high-level mode setting is passed, Clang will stop
       before doing a full link.  While Clang  is  highly  integrated,	it  is
       important to understand the stages of compilation, to understand how to
       invoke it.  These stages are:

       Driver The clang executable is actually a small driver  which  controls
	      the  overall  execution  of  other  tools  such as the compiler,
	      assembler and linker.  Typically you do  not  need  to  interact
	      with  the  driver, but you transparently use it to run the other
	      tools.

       Preprocessing
	      This stage handles tokenization of the input source file,  macro
	      expansion, #include expansion and handling of other preprocessor
	      directives.  The output of this stage is typically called a ".i"
	      (for  C),  ".ii"	(for  C++), ".mi" (for Objective-C), or ".mii"
	      (for Objective-C++) file.

       Parsing and Semantic Analysis
	      This stage  parses  the  input  file,  translating  preprocessor
	      tokens  into a parse tree.  Once in the form of a parse tree, it
	      applies semantic analysis to compute types  for  expressions  as
	      well  and  determine whether the code is well formed. This stage
	      is responsible for generating most of the compiler  warnings  as
	      well  as	parse errors. The output of this stage is an "Abstract
	      Syntax Tree" (AST).

       Code Generation and Optimization
	      This stage translates an AST into  low-level  intermediate  code
	      (known as "LLVM IR") and ultimately to machine code.  This phase
	      is responsible for optimizing the generated  code  and  handling
	      target-specific  code  generation.   The output of this stage is
	      typically called a ".s" file or "assembly" file.

	      Clang also supports the use of an integrated assembler, in which
	      the  code  generator produces object files directly. This avoids
	      the overhead of generating the ".s" file and of calling the tar-
	      get assembler.

       Assembler
	      This  stage runs the target assembler to translate the output of
	      the compiler into a target object file. The output of this stage
	      is typically called a ".o" file or "object" file.

       Linker This stage runs the target linker to merge multiple object files
	      into an executable or dynamic library. The output of this  stage
	      is typically called an "a.out", ".dylib" or ".so" file.

       Clang Static Analyzer

       The  Clang  Static  Analyzer is a tool that scans source code to try to
       find bugs through code analysis.  This tool uses many  parts  of  Clang
       and    is    built    into    the   same   driver.    Please   see   <-
       http://clang-analyzer.llvm.org> for more details  on  how  to  use  the
       static analyzer.

OPTIONS
   Stage Selection Options
       -E     Run the preprocessor stage.

       -fsyntax-only
	      Run the preprocessor, parser and type checking stages.

       -S     Run the previous stages as well as LLVM generation and optimiza-
	      tion stages and target-specific code  generation,  producing  an
	      assembly file.

       -c     Run  all	of  the above, plus the assembler, generating a target
	      ".o" object file.

       no stage selection option
	      If no stage selection option is specified, all stages above  are
	      run,  and  the linker is run to combine the results into an exe-
	      cutable or shared library.

   Language Selection and Mode Options
       -x <language>
	      Treat subsequent input files as having type language.

       -std=<standard>
	      Specify the language standard to compile for.

	      Supported values for the C language are:
		 c89
		 c90
		 iso9899:1990

		     ISO C 1990
		 iso9899:199409

		     ISO C 1990 with amendment 1
		 gnu89
		 gnu90

		     ISO C 1990 with GNU extensions
		 c99
		 iso9899:1999

		     ISO C 1999
		 gnu99

		     ISO C 1999 with GNU extensions
		 c11
		 iso9899:2011

		     ISO C 2011
		 gnu11

		     ISO C 2011 with GNU extensions
		 c17
		 iso9899:2017

		     ISO C 2017
		 gnu17

		     ISO C 2017 with GNU extensions

	      The default C language standard is gnu11, except on  PS4,  where
	      it is gnu99.

	      Supported values for the C++ language are:
		 c++98
		 c++03

		     ISO C++ 1998 with amendments
		 gnu++98
		 gnu++03

		     ISO C++ 1998 with amendments and GNU extensions
		 c++11

		     ISO C++ 2011 with amendments
		 gnu++11

		     ISO C++ 2011 with amendments and GNU extensions
		 c++14

		     ISO C++ 2014 with amendments
		 gnu++14

		     ISO C++ 2014 with amendments and GNU extensions
		 c++17

		     ISO C++ 2017 with amendments
		 gnu++17

		     ISO C++ 2017 with amendments and GNU extensions
		 c++2a

		     Working draft for ISO C++ 2020
		 gnu++2a

		     Working draft for ISO C++ 2020 with GNU extensions

	      The default C++ language standard is gnu++14.

	      Supported values for the OpenCL language are:
		 cl1.0

		     OpenCL 1.0
		 cl1.1

		     OpenCL 1.1
		 cl1.2

		     OpenCL 1.2
		 cl2.0

		     OpenCL 2.0

	      The default OpenCL language standard is cl1.0.

	      Supported values for the CUDA language are:
		 cuda

		     NVIDIA CUDA(tm)

       -stdlib=<library>
	      Specify  the  C++ standard library to use; supported options are
	      libstdc++ and libc++. If not specified, platform default will be
	      used.

       -rtlib=<library>
	      Specify  the  compiler runtime library to use; supported options
	      are libgcc and compiler-rt. If not specified,  platform  default
	      will be used.

       -ansi  Same as -std=c89.

       -ObjC, -ObjC++
	      Treat  source  input  files as Objective-C and Object-C++ inputs
	      respectively.

       -trigraphs
	      Enable trigraphs.

       -ffreestanding
	      Indicate that the file should be compiled  for  a  freestanding,
	      not a hosted, environment.

       -fno-builtin
	      Disable  special handling and optimizations of builtin functions
	      like strlen() and malloc().

       -fmath-errno
	      Indicate that math  functions  should  be  treated  as  updating
	      errno.

       -fpascal-strings
	      Enable support for Pascal-style strings with "\pfoo".

       -fms-extensions
	      Enable support for Microsoft extensions.

       -fmsc-version=
	      Set _MSC_VER. Defaults to 1300 on Windows. Not set otherwise.

       -fborland-extensions
	      Enable support for Borland extensions.

       -fwritable-strings
	      Make  all  string  literals  default to writable.  This disables
	      uniquing of strings and other optimizations.

       -flax-vector-conversions
	      Allow loose type checking rules for implicit vector conversions.

       -fblocks
	      Enable the "Blocks" language feature.

       -fobjc-abi-version=version
	      Select  the  Objective-C	ABI version to use. Available versions
	      are 1 (legacy "fragile" ABI),  2	(non-fragile  ABI  1),	and  3
	      (non-fragile ABI 2).

       -fobjc-nonfragile-abi-version=<version>
	      Select  the  Objective-C	non-fragile  ABI  version  to  use  by
	      default. This will only be used as the Objective-C ABI when  the
	      non-fragile ABI is enabled (either via -fobjc-nonfragile-abi, or
	      because it is the platform default).

       -fobjc-nonfragile-abi, -fno-objc-nonfragile-abi
	      Enable use of the Objective-C non-fragile ABI. On platforms  for
	      which  this  is  the  default  ABI,  it  can  be	disabled  with
	      -fno-objc-nonfragile-abi.

   Target Selection Options
       Clang fully supports cross compilation  as  an  inherent  part  of  its
       design.	 Depending  on how your version of Clang is configured, it may
       have support for a number of cross compilers, or  may  only  support  a
       native target.

       -arch <architecture>
	      Specify the architecture to build for.

       -mmacosx-version-min=<version>
	      When  building  for  Mac	OS X, specify the minimum version sup-
	      ported by your application.

       -miphoneos-version-min
	      When building for iPhone OS, specify the	minimum  version  sup-
	      ported by your application.

       -march=<cpu>
	      Specify that Clang should generate code for a specific processor
	      family  member  and  later.   For  example,   if	 you   specify
	      -march=i486,  the  compiler  is allowed to generate instructions
	      that are valid on i486 and later processors, but which  may  not
	      exist on earlier ones.

   Code Generation Options
       -O0, -O1, -O2, -O3, -Ofast, -Os, -Oz, -Og, -O, -O4
	      Specify which optimization level to use:
		 -O0  Means "no optimization": this level compiles the fastest
		 and generates the most debuggable code.

		 -O1 Somewhere between -O0 and -O2.

		 -O2 Moderate level of optimization which enables  most  opti-
		 mizations.

		 -O3  Like -O2, except that it enables optimizations that take
		 longer to perform or that may generate  larger  code  (in  an
		 attempt to make the program run faster).

		 -Ofast  Enables  all  the  optimizations  from -O3 along with
		 other aggressive optimizations that may violate  strict  com-
		 pliance with language standards.

		 -Os Like -O2 with extra optimizations to reduce code size.

		 -Oz Like -Os (and thus -O2), but reduces code size further.

		 -Og  Like  -O1. In future versions, this option might disable
		 different optimizations in order to improve debuggability.

		 -O Equivalent to -O2.

		 -O4 and higher
		     Currently equivalent to -O3

       -g, -gline-tables-only, -gmodules
	      Control debug information output.  Note that Clang debug	infor-
	      mation  works  best  at -O0.  When more than one option starting
	      with -g is specified, the last one wins:
		 -g Generate debug information.

		 -gline-tables-only Generate only line	table  debug  informa-
		 tion.	This  allows for symbolicated backtraces with inlining
		 information, but does not include any information about vari-
		 ables, their locations or types.

		 -gmodules  Generate  debug information that contains external
		 references to types defined in Clang modules  or  precompiled
		 headers  instead of emitting redundant debug type information
		 into every object file.  This option  transparently  switches
		 the  Clang  module format to object file containers that hold
		 the Clang module together with the debug  information.   When
		 compiling  a  program	that uses Clang modules or precompiled
		 headers, this option produces complete debug information with
		 faster compile times and much smaller object files.

		 This option should not be used when building static libraries
		 for distribution to other machines  because  the  debug  info
		 will  contain	references  to the module cache on the machine
		 the object files in the library were built on.

       -fstandalone-debug -fno-standalone-debug
	      Clang supports a number of optimizations to reduce the  size  of
	      debug  information in the binary. They work based on the assump-
	      tion that the debug type information can be spread out over mul-
	      tiple compilation units.	For instance, Clang will not emit type
	      definitions for types that are not needed by a module and  could
	      be  replaced  with  a  forward declaration.  Further, Clang will
	      only emit type info for a dynamic C++ class in the  module  that
	      contains the vtable for the class.

	      The  -fstandalone-debug  option  turns  off these optimizations.
	      This is useful when working with 3rd-party libraries that  don't
	      come  with  debug  information.	This is the default on Darwin.
	      Note that Clang will never emit type information for types  that
	      are not referenced at all by the program.

       -fexceptions
	      Enable  generation of unwind information. This allows exceptions
	      to be thrown through Clang compiled stack frames.  This is on by
	      default in x86-64.

       -ftrapv
	      Generate	code to catch integer overflow errors.	Signed integer
	      overflow is undefined in C. With this flag, extra code is gener-
	      ated to detect this and abort when it happens.

       -fvisibility
	      This flag sets the default visibility level.

       -fcommon, -fno-common
	      This flag specifies that variables without initializers get com-
	      mon linkage.  It can be disabled with -fno-common.

       -ftls-model=<model>
	      Set the default thread-local storage  (TLS)  model  to  use  for
	      thread-local  variables.	Valid  values  are:  "global-dynamic",
	      "local-dynamic", "initial-exec" and "local-exec". The default is
	      "global-dynamic".  The  default model can be overridden with the
	      tls_model attribute. The compiler will  try  to  choose  a  more
	      efficient model if possible.

       -flto, -flto=full, -flto=thin, -emit-llvm
	      Generate	output	files  in LLVM formats, suitable for link time
	      optimization.  When used with -S this generates LLVM  intermedi-
	      ate  language assembly files, otherwise this generates LLVM bit-
	      code format object files (which may  be  passed  to  the	linker
	      depending on the stage selection options).

	      The  default  for  -flto is "full", in which the LLVM bitcode is
	      suitable for monolithic Link Time Optimization (LTO), where  the
	      linker merges all such modules into a single combined module for
	      optimization.  With  "thin",  ThinLTO  compilation  is   invoked
	      instead.

   Driver Options
       -###   Print (but do not run) the commands to run for this compilation.

       --help Display available options.

       -Qunused-arguments
	      Do not emit any warnings for unused driver arguments.

       -Wa,<args>
	      Pass the comma separated arguments in args to the assembler.

       -Wl,<args>
	      Pass the comma separated arguments in args to the linker.

       -Wp,<args>
	      Pass the comma separated arguments in args to the  preprocessor.

       -Xanalyzer <arg>
	      Pass arg to the static analyzer.

       -Xassembler <arg>
	      Pass arg to the assembler.

       -Xlinker <arg>
	      Pass arg to the linker.

       -Xpreprocessor <arg>
	      Pass arg to the preprocessor.

       -o <file>
	      Write output to file.

       -print-file-name=<file>
	      Print the full library path of file.

       -print-libgcc-file-name
	      Print  the  library path for the currently used compiler runtime
	      library ("libgcc.a" or "libclang_rt.builtins.*.a").

       -print-prog-name=<name>
	      Print the full program path of name.

       -print-search-dirs
	      Print the paths used for finding libraries and programs.

       -save-temps
	      Save intermediate compilation results.

       -save-stats, -save-stats=cwd, -save-stats=obj
	      Save internal code generation (LLVM) statistics to a file in the
	      current  directory (-save-stats/"-save-stats=cwd") or the direc-
	      tory of the output file ("-save-state=obj").

       -integrated-as, -no-integrated-as
	      Used to enable and disable, respectively, the use of  the  inte-
	      grated  assembler.  Whether  the	integrated  assembler is on by
	      default is target dependent.

       -time  Time individual commands.

       -ftime-report
	      Print timing summary of each stage of compilation.

       -v     Show commands to run and use verbose output.

   Diagnostics Options
       -fshow-column, -fshow-source-location, -fcaret-diagnostics,  -fdiagnos-
       tics-fixit-info,       -fdiagnostics-parseable-fixits,	    -fdiagnos-
       tics-print-source-range-info,   -fprint-source-range-info,   -fdiagnos-
       tics-show-option, -fmessage-length
	      These options control how Clang  prints  out  information  about
	      diagnostics  (errors  and warnings). Please see the Clang User's
	      Manual for more information.

   Preprocessor Options
       -D<macroname>=<value>
	      Adds an implicit #define into the  predefines  buffer  which  is
	      read before the source file is preprocessed.

       -U<macroname>
	      Adds an implicit #undef into the predefines buffer which is read
	      before the source file is preprocessed.

       -include <filename>
	      Adds an implicit #include into the predefines  buffer  which  is
	      read before the source file is preprocessed.

       -I<directory>
	      Add  the	specified  directory  to  the  search path for include
	      files.

       -F<directory>
	      Add the specified directory to the  search  path	for  framework
	      include files.

       -nostdinc
	      Do  not  search  the  standard  system  directories  or compiler
	      builtin directories for include files.

       -nostdlibinc
	      Do not search the standard system directories for include files,
	      but do search compiler builtin include directories.

       -nobuiltininc
	      Do not search clang's builtin directory for include files.

ENVIRONMENT
       TMPDIR, TEMP, TMP
	      These environment variables are checked, in order, for the loca-
	      tion to  write  temporary  files	used  during  the  compilation
	      process.

       CPATH  If  this	environment  variable  is  present, it is treated as a
	      delimited list of paths  to  be  added  to  the  default	system
	      include  path  list.  The  delimiter  is	the platform dependent
	      delimiter, as used in the PATH environment variable.

	      Empty components in the environment variable are ignored.

       C_INCLUDE_PATH,	  OBJC_INCLUDE_PATH,	 CPLUS_INCLUDE_PATH,	 OBJC-
       PLUS_INCLUDE_PATH
	      These environment variables specify  additional  paths,  as  for
	      CPATH,  which are only used when processing the appropriate lan-
	      guage.

       MACOSX_DEPLOYMENT_TARGET
	      If -mmacosx-version-min is unspecified, the  default  deployment
	      target  is read from this environment variable. This option only
	      affects Darwin targets.

BUGS
       To report bugs, please visit <http://llvm.org/bugs/>.  Most bug reports
       should  include	preprocessed  source files (use the -E option) and the
       full output of the compiler, along with information to reproduce.

SEE ALSO
       as(1), ld(1)

AUTHOR
       Maintained by the Clang / LLVM Team (<http://clang.llvm.org>)

COPYRIGHT
       2007-2019, The Clang Team



Apple Clang 10.0.1		 Apr 02, 2019			      CLANG(1)
